Thank you very much for your answer.
Assuming there are such scanners, what would be the correct SANE command
Many production scanners do support this feature. Most of these scanners
scan only B&W and grayscale but not necessarily at low resolutions (it is
not very uncommon 600 dpi and up). If the scanner scans compressed then the
amount of memory needed to store an image in the scanner buffer is minimal,
but scan ahead may be supported also for uncompressed data (how many pages
is the scanner able to scan before to fill completely the buffer depends on
the buffer and image size and the speed the application is able to pull out
images from the buffer). All those scanners when used in page by page scan
mode (i.e. scan synchronously with the driver/application) are not able
usually to sustain their maximum scan speed.
The particular scanner I want to try to scan in scan ahead mode from it
using SANE is Fujitsu M4099D.
I am very interested to know the correct SANE command sequence/procedure for
such a scan-ahead acquisition sequence.
> -----Original Message-----
> From: Peter Kirchgessner [mailto:email@example.com]
> Sent: March 30, 2001 3:09 PM
> To: firstname.lastname@example.org
> Subject: Re: Scan ahead
> Hello Marius,
> I dont know a scanner that can store a single frame completely. For an
> A4 scan at 600 dpi with 24bit you would need about 100MB of memory.
> Maybe this works for b/w scans at low resolution. But in that case I
> suppose the scanner will not accept to start a new scan when the image
> has not been read completely.
> > JFL Sane Dev wrote:
> > Hi,
> > I am a beginner with SANE. Could anyone tell me please how should a
> > scan-ahead (automatic scan, the scanner scans asynchronously at
> > highest possible speed to its internal memory buffer, the
> driver reads
> > images at its own speed from the scanner buffer) image acquisition
> > sequence be implemented in a SANE session?
> > If the driver starts the scanner in automatic mode at first
> > it receives, would the application have to not request sane_cancel
> > until all images are transferred?
> > If the application would call repeatedly sane_start +
> > sane_read_until_SANE_STATUS_EOF for each image, and then call
> > sane_cancel when sane_start (or sane_read) returns
> > SANE_STATUS_NO_DOCS? Would this be the correct procedure?
> > Thanks,
> > Marius Niculescu
> Peter Kirchgessner
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